走进rxjs的世界 - 万物皆流 - Everything is a stream

The caller of our pollTasks() method just gets an observable, which is emitting content every 10 seconds.

调用pollTasks方法，只会返回一个Observable对象，这个Observable对象subscribe之后，会每隔10秒产生内容。调用unsubscribe关闭。

Also the flatMapLatest call is really interesting – any calls generated by previous events are canceled, including their in-flight HTTP method calls. Try doing that with a promise!

flagMapLatest是一个强力方法，这里将其当作一种engine使用：所有基于之前发生的事件触发的调用都会自动被cancel，包括正在进行中的in-flight HTTP调用。很难想象使用promise实现类似的方法，会花费多大的工作量。

参考文献